NEW YORK - Nine times out of 10, cutting costs makes sense. It's painless to go without an expensive lunch every day or the latest and most up-to-date television or cell phone. But there are some purchases that you shouldn't cut back on. In fact, cutting back on these can do more harm than good.

From Liz Pulliam Weston of MSN Money, consider these four occasions when you shouldn't cut back:

Car maintenance: If you ignore car maintenance, it will only come back to bite you. Follow your car manual and take your car in for tune ups at the recommended mileage. You should also not ignore any potential problems, out-of-place sounds or oil leaks. Delaying dealing with these issues may only cost you more in the end when they become larger problems. You should also take the time to find a good mechanic. Even if they charge a little more than others, it will be worth it in the long run.

Safety for the home: To be properly prepared for a fire, most experts say you should hang a smoke detector outside every bedroom in addition to a carbon-monoxide detector on every floor. You should also own escape ladders for every room above the first floor.

Faster Internet connection: Prices of high-speed Internet access have come down in recent years. Cable and DSL connections can be had in some areas for a mere $10 more than dial-up. That difference is more than worth the time you will save with the faster connection. Do some research in your area to find out about your high-speed Internet options. If you discover that they are not much more expensive than dial-up, consider switching.

Comfortable mattress: You can find a good mattress without having to spend thousands. Good mattresses can be bought for less than $1,000, and with sales and promotions, you're likely to save an additional 30 percent to 50 percent. Don't try to get away with buying a cheap one or a used one. Remember you're going to be sleeping on it every night.